When a user of a communication terminal such as a telephone with which the user performs voice communications has the communication terminal cooperated with a data terminal such as a PC on one-on-one basis, it is called “pairing”. Through pairing the communication terminal with the data terminal, the voice communication and document data containing texts, images, and the like can be shared with other users in real time, and those can be viewed, edited cooperatively, etc.
When users each having paired communication terminal and data terminal communicate with each other via the respective communication terminals, the mutual data terminals come under a condition where those are being connected on one-on-one basis as in an ad hoc mode of radio LAN. Thus, the users can share data mutually. In that case, pairing may be done in advance and then communication may be started or pairing may also be started during the communication. It is impossible for a third party to make access to the data terminals connected mutually.
At that time, the communication terminal and the data terminal are paired necessarily on one-on-one basis, and already paired communication terminal or the data terminal is not paired with other communication terminal or data terminal unless the pairing state is released. Further, communication terminals are not paired with each other, and data terminals are not paired with each other, either.
As techniques for enabling such pairing, there are following techniques. Patent Document 1 discloses a technique with which both users having voice communication by using communication terminals input terminal discriminating information such as the telephone number of the own communication terminals to the data terminals to pair the communication terminal and the data terminal so as to start data sharing between the data terminals of the both users.
In Patent Documents 2-7, disclosed are methods for pairing radio devices having a short-distance communication function such as Bluetooth or wireless USB with each other. Patent Document 2 is a method which makes it easy to select a radio device to be paired among a great number of radio devices. First, a radio device that is trying to find a radio device increases output of radio waves for discovering the radio device gradually, and the discovered radio device and the reached range of the radio waves at that point are stored in a corresponding manner. Then, each of the discovered radio devices and the reached ranges are displayed in a corresponding manner for allowing the user to select the radio device to be paired.
The technique disclosed in Patent Document 3 is targeted at simplifying the pairing work of a television receiver set and an imaging device. Terminal discriminating information of the television receiver set is displayed on a screen of the television receiver set. When a user picks it up with the imaging device, the terminal discriminating information extracted from the picked up video is coded along with the discriminating information of the imaging device. Then, it is transmitted to the television receiver set by radio communication, and authentication and pairing are conducted. With the technique disclosed in Patent Document 4, first, PIN codes are exchanged mutually by using an infrared communication function between devices having a radio communication function using radio waves and a radio communication function using infrared rays, then authentication and pairing are conducted with the radio communication function using radio waves by utilizing the PIN codes which have already been exchanged.
Patent Document 5 discloses a communication device which performs radio communication with an electronic camera after conducting authentication by comparing a PIN code received from the electronic camera with a PIN code inputted by a user. Patent Document 6 discloses a technique with which a slave device and a master device mutually exchange IDs to mutually select and register a pairing partner. Patent Document 7 discloses a technique which adjusts transmission intervals of beacons which are exchanged mutually between devices for pairing.    Patent Document 1: Japanese Unexamined Patent Publication 2005-012380    Patent Document 2: Japanese Patent No. 3865124    Patent Document 3: Japanese Unexamined Patent Publication 2006-135930    Patent Document 4: Japanese Unexamined Patent Publication 2002-073565    Patent Document 5: Japanese Unexamined Patent Publication 2002-095047    Patent Document 6: Japanese Unexamined Patent Publication 2005-328295    Patent Document 7: Japanese Unexamined Patent Publication 2006-148471